Billy the Kid is a well-known outlaw who travelling with/protecting a girl named Axel. When Billy tried to steal Riot, the magical book of the Western Church, Axel, its guardian, chased after and then killed Billy. When Billy's blood hit Riot, it decided to make a deal with Billy: full resurrection for Billy if he promises to protect Riot and Axel. Billy agrees to the deal. Meanwhile, in the Eastern Church, where the magical book Phantom is, evil forces lead by Cain want Riot so that he can use the powers of both books for his own personal gain, which includes reviving his friend Abel, who is Axel's older brother. Also, Billy is chased after by Ritchie, the friend he killed years ago, who somehow is revived and wants revenge.